Field of the Invention
The present invention relates to a magnetic sensor and a current sensor including the magnetic sensor, and more particularly relates to a fluxgate magnetic sensor and a current sensor including the fluxgate magnetic sensor.
Description of Related Art
A fluxgate magnetic sensor is known as a magnetic sensor that detects an external magnetic field. International Publication WO2009/093178 and Japanese Patent Application Laid-open No. 2011-112634 describe examples of the fluxgate magnetic sensor.
The fluxgate magnetic sensor described in International Publication WO2009/093178 has a configuration in which a coil is wound around a fluxgate core made of an amorphous magnetic metal or the like, and can detect a magnetic field occurring according to a current flowing through a bus bar. However, the fluxgate magnetic sensor described in International Publication WO2009/093178 has an open magnetic circuit structure and thus the number of windings of the coil needs to be increased to obtain a sufficient inductance, which is not suitable for downsizing.
Japanese Patent Application Laid-open No. 2011-112634 discloses a fluxgate magnetic sensor having a closed magnetic circuit structure. The fluxgate magnetic sensor described in Japanese Patent Application Laid-open No. 2011-112634 has a low resistance portion made of permalloy and a high resistance portion made of ferrite, which are joined together in a ring shape to provide the closed magnetic circuit structure. In Japanese Patent Application Laid-open No. 2011-112634, the fluxgate magnetic sensor is formed by winding a coil around the low resistance portion made of permalloy.
However, because the coil is wound around the low resistance portion made of permalloy in the fluxgate magnetic sensor described in Japanese Patent Application Laid-open No. 2011-112634, there is a problem that the measurement range of the magnetic sensor is restricted by the saturation flux density of the lower resistance portion and the measurement range is narrow.